The present disclosure relates to metal-containing surfaces, and more particularly, to methods to mitigate formation of tin whiskers on tin-containing surfaces.
Pure tin (Sn) plating has replaced tin-lead alloy solders in many electrical applications, for example, electrical hardware, circuit board traces, component leads, and ground planes. Replacing tin-lead alloy solders with pure tin plating is driven, in part, by environmental and health concerns about lead.
The “whisker” or “tin whisker” phenomenon is a failure mode associated with some electronic devices that use a number of low melting point elements (e.g., tin (Sn), cadmium (Cd), zinc (Zn), nickel (Ni), and indium (In)) in operations such as soldering. As shown in FIG. 1, tin whiskers 101 may be formed from a pure (or substantially pure) tin-based surface 100. Whiskers may also form on other surfaces, such as nickel surfaces. Generally, metal whiskers have a small mass (for example, less than 100 micrograms) with a high surface area-to-volume ratio. Because metal whiskers are conductive and can carry high current, they may result in electronic shorting failures.